纤维素热裂解反应机理数值模拟

A detailed mechanism analysis of cellulose pyrolysis was carried out according to the previous experimental results. On the basis of the Brodio-Shafizadeh model, a modified two-stage model was proposed to simulate the formation and decomposition of active cellulose (AC) and several main organic compounds, such as levoglucosan (LG), hydroxyl-acetaldehyde (HAA), acetol and furfural etc. During pryolysis, the temperature rise of cellulose can be divided into three stages. In the second stage, cellulose undergoes a main decomposition process in which the reaction temperature remains rather low because of the endothermic cracking of glucosidic bond of AC during the formation of LG. The components density of bio-oil, including LG and other competitive compounds, increased rapidly with the increase of temperature during the first stage. However, in the main decomposition process, LG density in bio-oil had an obvious decrease, while the competitive products appeared to increase gradually, which means the ring-opening and reforming reaction of pyranoid ring are superior to LG formation in high temperature.The secondary reaction of volatile components occurs largely in gaseous phase rather than in the solid phase. Short residence time of volatile materials in high temperature region will be advantageous to a high production of LG,which may otherwise decompose quickly under high temperature. An optimum yield of LG could be obtained when radiant source temperature is in the range of 730---920K and gas residence time is less than 1 s. In addition, the reaction temperature has a stronger effect than gas residence time on the formation of HAA, acetol, formaldehyde and furfural etc.     

用UV/H2O2,UV/O3,UV/H2O2/O3催化处理城市固体垃圾填埋渗出物

The performance of UV/H2O2, UV/O3, and UV/H2O2/O3 oxidation systems for the treatment of municipal solid-waste landfill leachate was investigated. Main objective of the experiment was to remove total organic carbon (TOC), non-biodegradable organic compounds (NBDOC) and color. In UV/H2O2 oxidation experiment, with the increase of H2O2 dosage, removal efficiencies of TOC and color along with the ratio of biochemical oxygen demand (BOD) to chemical oxygen demand (COD) of the effluent were increased and a better performance was obtained than the system H2O2 alone. In UV/H2O2 oxidation, under the optimum condition H2O2 (0.2 time), removal efficiencies of TOC and color were 78.9% and 95.5%, respectively, and BOD/COD ratio was significantly increased from 0.112 to 0.366. In UV/O3 oxidation, with the increase of O3 dosage, removal efficiencies of TOC and color along with BOD/COD ratio of the effluent were increased and a better performance was obtained than the system O3 alone. Under the optimum condition UV/O3     

N, O-羧甲基壳聚糖复合纳滤膜的制备及其对酒厂发酵废水的截留效果

N, O-carboxymethyl chitosan （NOCC） composite nanofiltration （NF） membranes were prepared by coating and cross-linking. The fermentation effluent from a wine factory was treated with the resulting NOCC/polysulfone （PSF） composite NF membranes. The permeate flux and the removal efficiencies of the resulting NF membranes for the color, chemical oxygen demand （CODcr）, total organic carbon （TOC）, and conductivity of the fermentation effluent were investigated in relation to the driving pressure, the feed flow, and the operation time. The permeate flux and the removal efficiencies were found to increase with the increase of the driving pressure or the feed flow. At 0.40 MPa and ambient temperature the removal efficiencies were 95.5%, 70.7%, 72.6%, and 31.6% for color, CODcr, TOC, and conductivity, respectively. The membrane was found to be stable over a 10-h ooeration for the fermentation effluent treatment.     

高压乙醇中的无限稀释扩散系数:实验测定与模型评价

The infinite diffusion coefficients of benzene, toluene, naphthalene, pyridine and p-nitroaniline in ethanol were measured by Taylor dispersion technique under 318-473 K and 0-16 MPa. The measurement accuracy of the established apparatus was first checked. The measured diffusion coefficient of the five organic solutes in ethanol did not change with pressure at low temperature, but it was significantly reduced with pressure increase when the temperature is higher than 373 K. Of the correlations available for polar solvents, the modified Wilke-Chang equation, the Yang-Zhang equation as well as the He-Yu equation were used to calculate the infinite diffusion coefficient. At low temperature,the three equations all agreed well with experimental results for both polar and non-polar solutes.However, the prediction accuracy was decreased sharply when the temperature was higher than 373 K,where the association factor of the solvent was varied with temperature as well as pressure.     

苯在超临界水中的分子动力学研究

Microscopic structure and diffusion properties of benzene in ambient water (298 K, 0.1 MPa) and supercritical water (673--773 K, 25---35 MPa) are investigated by molecular dynamics simulation with site-site models.It is found that at the ambient condition, the water molecules surrounding a benzene molecule form a hydrogen bond network. The hydrogen bond interaction between supercritical water molecules decreases dramatically under supercritical conditions. The diffusion coefficients of both the solute molecule and solvent molecule at supercritical conditions increase by 30---180 times than those at the ambient condition. With the temperature approaching the critical temperature, the change of diffusion coefficient with pressure becomes pronounced.     

滴流床中乙醛液相氧化合成过氧乙酸新工艺

In this paper,shorter residence time（a few minutes）with high yield in the trickle bed process for per- acetic acid synthesis by acetaldehyde liquid phase oxidation can be realized on the selected packing material SA-5118.For acetaldehyde in acetone with ferric ion as catalyst,the optimized process conditions were presented. The main factors influencing the yield,selectivity and conversion are residence time,temperature and acetaldehyde concentration,respectively.The temperature range checked is from 30 to 65℃.High yield of 81.53%with high se- lectivity of 91.84?n be obtained at higher temperature of 55℃when the residence time is 5.5min and the acet- aldehyde concentration is 9.85%（by mass）.And there is a critical acetaldehyde concentration point（Cccp）between 18%and 19.5%（by mass）.At temperature less than 55℃,the highest yield to peracetic acid at each temperature level increases with temperature when the acetaldehyde concentration is below Cccp and decreases with temperature when the acetaldehyde concentration is above Cccp.     

Simulation of hydrocarbons pyrolysis in a fast-mixing reactor

Currently, thermal decomposition of hydrocarbons for the production of basic petrochemicals (ethylene, propyl-ene) is carried out in steam-cracking processes. Aside from the conventional method, under consideration are alternative ways purposed for process intensification. In the context of these activities, the method of high-temperature pyrolysis of hydrocarbons in a heat-carrier flow is studied, which differs from previous ones and is based on the ability of an ultra-short time of feedstock/heat-carrier mixing. This enables to study the pyrolysis process at high temperature (up to 1500 K) at the reactor inlet. A set of model experiments is conducted on the lab scale facility. Liquefied petroleum gas (LPG) and naphtha are used as a feedstock. The detailed data are obtain-ed on temperature and product distributions within a wide range of the residence time. A theoretical model based on the detailed kinetics of the process is developed, too. The effect of governing parameters on the pyrolysis process is analyzed by the results of the simulation and experiments. In particular, the optimal temperature is detected which corresponds to the maximum ethylene yield. Product yields in our experiments are compared with the similar ones in the conventional pyrolysis method. In both cases (LPG and naphtha), ethylene selectivity in the fast-mixing reactor is substantial y higher than in current technology.     

一氧化碳在苯酚+乙醇中的溶解度测量和关联

The solubility of carbon monoxide in phenol＋ethanol mixed solvents at elevated pressures is reported in this article. The experimental results revealed the influence of pressure on the solubility of CO in phenol＋ethanol mixtures. These mixtures are a poorer solvent for carbon monoxide. The solubility of CO is a linear function of pressure, and the extended Henry＇s constants were presented at different concentrations of phenol. The cubic Soave-Redlich-Kwong equation of state was used to correlate the experimental gas liquid equilibrium data and to predict the solubility of CO. At the same time, the binary interaction parameters, kO, for CO-phenol, CO-ethanol and phenol-ethanol systems were estimated by fitting experimental GLE data at 303.15 K and at 2.0-9.0 MPa. Hence, a model was suggested for the solubility of CO in phenol＋ethanol mixed solvents. The agreement between experimental and calculated solubilities with the proposed model was rather satisfactory.     

Easy removing of phenol from wastewater using vegetable oil-based organic solvent in emulsion liquid membrane process

Phenol is considered as pollutant due to its toxicity and carcinogenic effect.Thus,variety of innovative methods for separation and recovery of phenolic compounds is developed in order to remove the unwanted phenol from wastewater and obtain valuable phenolic compound.One of potential method is extraction using green based liquid organic solvent.Therefore,the feasibility of using palm oil was investigated.In this research,palm oil based organic phase was used as diluents to treat a simulated wastewater containing 300×10~(-6) of phenol solution using emulsion liquid membrane process(ELM).The stability of water-in-oil(W/O) emulsion on diluent composition and the parameters affecting the phenol removal efficiency and stability of the emulsion;such as emulsification speed,emulsification time,agitation speed,surfactant concentration,pH of external phase,contact time,stripping agent concentration and treat ratio were carried out.The results of ELM study showed that at ratio7 to 3 of palm oil to kerosene,5 min and 1300 r·min~(-1) of emulsification process the stabile primary emulsion were formed.Also,no carrier is needed to facilitate the phenol extraction.In experimental conditions of500 r·min~(-1) of agitation speed,3%Span 80,pH 8 of external phase,5 min of contact time,0.1 mol·L~(-1) NaOH as stripping agent and 1:10 of treat ratio,the ELM process was very promising for removing the phenol from the wastewater.The extraction performance at about 83%of phenol was removed for simulated wastewater and an enrichment of phenol in recovery phase as phenolate compound was around 11 times.     

高温高压下湿空气循环中增湿塔的计算研究

Humidification is an important step in humid air turbine system. The calculation on humidification is carried out at 423.15—573.15K, 5—15MPa. The results suggest that to produce high-enthalpy moist air, high water temperature and large water flow are needed. The water temperature is the most sensitive parameter to the humidification tower. And it is better for the humidification tower to work at temperature higher than 523 K when the system pressure is higher than 5 MPa. The comparison between the model used in this paper and ideal model shows that the ideal model can be used in simulation to simply the calculation when the temperature is lower than 473 K and pressure is lower than 5 MPa.     

苯胺在超临界水中氧化反应动力学的研究

对苯胺在超临界水中的氧化反应进行了研究。发现随温度升高和停留时间延长,苯胺去除率和COD去除率增大,并且只有在温度高于898.15K条件下,苯胺氧化的COD去除率才有可能达到90％以上。在873.15K～898.15K范围内,温度对苯胺氧化的COD去除率有较显著的影响。在673.15K～748.15K、25.0MPa、300％过氧量、2.351×10-4mol(L-1苯胺浓度条件下,苯胺反应级数为1.554,反应的活化能为2.96(104J(mol-1,频率因子为6.69×103。     

湿式氧化法处理苯酚、苯胺和硝基苯废水的研究

采用湿式氧化法分别处理含苯酚、苯胺和硝基苯的废水,研究了反应温度(160～220℃)对氧化反应的影响。苯酚的氧化经历两步,即诱导期和快反应期,而苯胺的氧化反应无诱导期。有机污染物的反应活性与其结构和氧化反应的模式有关,在一定的时间内,3种有机污染物的氧化去除率的次序为:苯酚>苯胺>硝基苯。     

超临界水氧化法去除废水有机氮的工艺和动力学研究

<正> 引言 超临界水氧化法(SCWO)是一种新型高效的废水和废物处理技术.水在超临界条件下具有独特的物理化学性质,它能与非极性物质如烃类和其他有机物完全互溶,而无机物特别是盐类在超临界水中的溶解度很低.另外,超临界水可以与气体(如空气、氧气、二氧化碳等)完全互溶.这些性质使得超临界水作为反应介质的超临界水氧化法具有独特的优势.在超临     

水热氧化法处理焦化废水的可行性研究

以焦化废水为研究对象,采用水热氧化技术研究废水处理的技术可行性,具有重大的理论和实际应用价值。在连续式反应器中,研究了实际焦化废水中主要污染物指标COD、NH3-N的降解行为。采用水热法处理焦化废水对COD去除率可达90%以上,当温度高于500 K时,COD浓度可降至300 mg/L以下,达到三级排放标准(GB 13456-1992)。停留时间是NH3-N彻底去除的主要因素。在停留时间达到12.46 min、温度为581 K、压力为15 MPa的亚临界条件下,NH3-N浓度可降至2.6 mg/L,达到一级排放标准。     

超临界水氧化处理DDNP废水的动力学研究

采用间歇式超临界水氧化实验装置，以O2为氧化剂，在703-823K、压力24MPa、停留时间10-50s的条件下，进行了超临界水氧化DDNP模拟废水实验，COD去除率可达99％；建立了COD去除率宏观动力学方程。结果表明，超临界水氧化对处理DDNP是有效的，在超临界条件下，DDNP废水的COD去除率随着反应温度的升高和停留时间的延长而增加；在氧化剂过量2倍的情况下，DDNP超临界水氧化反应对有机物的反应级数为1．33级，对氧气为0．21级；反应活化能E。为30．7kJ／mol，指前因子A为61．97。     

ε-酸在超临界水中的氧化降解

实验研究了典型有机污染物ε -酸在超临界水中的氧化降解.结果表明,超临界水氧化技术能有效地降解废水中的有机污染物,COD去除率可达99%以上.随着反应温度的升高、压力的增大、停留时间的延长和初始废水浓度的增大,COD去除率也随之提高.ε-酸在超临界水中氧化降解的动力学方程为:-d[COD]/dt =9.75104exp(-8.3804/RT)[COD]1.06[O2]00.165     

Ni-B/SiO2催化剂上硝基苯选择加氢制备苯胺

以KBH4为还原剂,用浸渍-还原法制备了Ni-B/SiO2催化剂,并用于硝基苯催化加氢制苯胺的反应,讨论了制备条件（Ni、B用量及焙烧温度）及反应条件（压力、温度）对硝基苯的转化率及苯胺选择性的影响。结果表明,Ni-B/SiO2催化剂具有很高的催化活性。适当增加Ni和B的用量,可以提高催化剂对硝基苯的转化率和转化频率及苯胺的选择性。催化剂前驱体的焙烧温度在453K时,硝基苯的转化率可达到98.5%,对苯胺选择性为97.0%。过高的焙烧温度不利于催化剂活性的提高。适当提高加氢反应压力以及温度,可以提高催化剂的加氢活性及对苯胺的选择性。     

非晶态Ni-Mo-P催化剂上硝基苯加氢为苯胺及催化剂失活机理

引言苯胺是一种重要的有机中间体,广泛应用于聚氨酯、橡胶助剂和医药等领域[1-3]。硝基苯催化加氢法合成苯胺是目前应用较为广泛的工艺之一。其生产方法主要有硝基苯Fe粉还原法、苯酚氨碱法和硝基苯催化加氢法[4],其中,硝基苯催化加氢法     

膜-好氧组合工艺处理餐饮废水的研究

采用无机膜 -好氧组合工艺对高浓度餐饮废水 (COD 15 0 0 0mg/L)进行处理。考察了进水COD浓度、溶解氧浓度、水力停留时间对好氧反应器处理效果的影响。结果表明 ,当水力停留时间大于 5 .6h时 ,废水的COD去除率高于 90 % ,温度对处理效果影响不大。对好氧出水用无机膜进行分离 ,最终出水COD小于 2 5mg/L ,浊度小于 1NTU。     

湿式过氧化物氧化技术处理高浓度有毒有机废水研究

采用湿式过氧化物氧化技术(WPO)处理苯酚丙酮装置某化工厂产生的高浓度有毒有机废水,并在WPO的基础上投加活性炭,加强催化氧化效果。通过单因素实验确定反应温度160℃,反应时间1h,进水pH值为3.0,H2O2投送加量控制在H2O2/COD=0.5,FeSO4按照n[Fe2+]/n[H2O2]=0.1的比例投加,在活性炭催化作用的强化下,COD和苯酚的去除率分别可以达到90%和99%以上。